The Land Before Time X: The Great Longneck Migration

Littlefoot and his friends return in another adventure. But this time, they aren't the smallest dinosaurs in the valley anymore.

Littlefoot and his pals set off in search of a "stone of cold fire" that fell from the night sky. Since he's the only one who has seen it though, nobody really believes him. Petrie's uncle Pterano offers support only because he thinks the stone has secret powers and wants it for himself but conceals this from the rest. The young dinos must figure out the truth, before Pterano gets the power.

Littlefoot befriends with a mysterious, fun-loving dolphin-like creature named Mo, who is trapped in "new water" caused by heavy rain. The gang then goes on an adventure to the "big water" to bring Mo home.

Littlefoot's grandfather narrates the story about the Lone Dinosaur that killed a Sharptooth. A giant monolith formed after the fight and if it's destroyed, bad luck will loom over the valley.

When the water supply to the Great Valley is blocked, Littlefoot and his friends must cooperate with a group of bullies to find the reason the cause.